1. Field of the Invention
This invention relates to portable external memory devices. Specifically, the invention relates to apparatus, systems, and methods for deliberately preventing access to data stored in a non-volatile memory device.
2. Description of the Related Art
Computer users frequently use portable storage devices such as universal serial bus (USB) keys and Smart Cards for storage and transfer of computer data. Portable storage devices interoperate with host computers to store and retrieve data. Data is typically stored on the portable storage device in non-volatile memory. A portable storage device may be disconnected from a power source such as a host computer without losing data stored in the non-volatile memory. Portable storage devices assist in many activities, including data transport, data backup, and data security.
Data security is perhaps one of the most important uses of portable storage devices. Large amounts of confidential data may be downloaded from a host computer to a portable storage device for transport. During transfer, the data does not travel over the Internet and is not accessible by networking technology. Once transport is complete, the portable storage device is connected to a host computer and the user can access the stored data. The portable storage device may be disconnected from the host computer and kept in a vault or other secure location, completely isolated from a computer network.
Sensitive files such as a company's private key, confidential designs, encryption algorithms, and strategic plans may be securely stored on portable storage devices. By storing data only onto a portable storage device, security issues related to storing sensitive data on a hard drive can be avoided. Even when a computer system deletes files from a hard drive, the data may be recovered from the drive with sophisticated data recovery programs and techniques.
Portable storage devices may be used to facilitate secure transport of data from one computer to another. It is often convenient to save data from a host computer onto a portable storage device for transport. Although network transport across the Internet or across a company intranet may also be used, many people prefer to use a portable storage device for transporting important files in certain situations. As an example, an employee taking a trip to a new city may not know where the employee will be working in the new city. It would be impossible to send the data to a destination computer that is unknown at the beginning of the trip. By carrying the important data on a portable storage device, the data travels with the employee and is available at whatever computer the employee finally uses.
Portable storage devices also serve data backup purposes. A home user may store a backup copy of financial data onto a portable storage device as part of a data protection plan. Portable storage devices use non-volatile memory technologies that do not lose data due to power surges or power outages. In addition, archival copies of data files may be stored on portable storage devices. Modern portable storage devices are small and may hold many hundreds of megabytes worth of data. Multiple versions of a single archive may be stored on a single portable storage device.
As portable storage devices become more common, administrators worry that data stored on the portable storage devices may be stolen or misused. Certain conventional devices provide means for destroying data on portable storage devices in response to tampering with the device. Efforts to disassemble devices cause certain devices to become non-functional. However, these conventional devices do not address the need to deliberately quickly, and actively destroy data on a portable memory device.
Other conventional devices facilitate the destruction of circuitry used for memory access. Such devices may destroy the circuitry normally used to access data on the device or may even partially destroy a chip used for storing data on the device. However, such devices do not ensure that memory stored in the memory chip itself will be completely destroyed. Individuals intent on gaining unauthorized access to data on such a memory device may remove the memory chip and recover portions of the data using sophisticated probing equipment. These portions of data may be sufficient to disclose confidential information the portable storage device owner believed was destroyed. These devices also do not allow for the manual, deliberate, and logical erasing of data on the portable storage device such that the device may be reused in the future.
As an example, an embassy data officer may be charged with the safekeeping of embassy data files. The data officer may safeguard portable storage devices containing encryption algorithms, top secret treaties, and strategic operations plans. The data officer would be charged with destroying the portable data devices if the embassy's security is threatened. The data officer would need to quickly and effectively either erase the devices or destroy them in such a way that no data would be retrievable from the devices. The data officer may need to be able to do this quickly without use of a host computer.
As another example, a retail movie rental company may store movies, games, or other digital content on portable storage devices for use by customers. When the portable storage device is returned, or when a title is taken out of circulation (i.e., Due to an expired licensing agreement), it would be important to prevent the device from being used again if the device is discarded to protect the copyrighted movie on the device. This could be done either by erasing the device or by destroying the memory chips on the device. The clerk who receives the returned rental unit may need to disable the portable storage device quickly and without the use of a host computer.
Under ordinary circumstances, a portable memory device is returned to the host computer for data erasure. Any host computer capable of writing data to a portable memory device can also erase the data on a portable memory device. This process can be time consuming. The host computer needs to be powered on. The computer needs to individually erase each device. Complete erasure requires the host computer to access all storage bytes on the device. However, some situations require that a portable memory device be erased quickly and securely without the use of a host computer. The embassy data officer may need to erase or disable several devices before an impending coup. The video rental clerk may need to quickly erase or disable a rentable portable storage device. Following the grading of a test stored on several hundred USB memory keys, a professor may want to erase the memory keys quickly and deliberately to guard test answers from inadvertent disclosure.
In each of these scenarios, the ability to deliberately and quickly destroy the data in a portable memory device without the use of a host computer is highly desirable. Consequently, a need exists for a process, apparatus, and system that allow for the quick, deliberate, and efficient prevention of access to data stored on portable memory devices without the assistance of a host computer. Such a system must either completely erase the memory on a portable storage device or completely destroy the memory circuitry that holds the data on such a device in such a way that no data may be retrieved from the device. Beneficially, such a process, apparatus, and system would reduce the time needed to clear such devices and ensure that data on such devices not be used improperly.